Universal serial bus repeater

ABSTRACT

A method and system for communicating data between two devices are described herein. The method detects an electrical signal of a first protocol from a first device in a repeater, wherein the first protocol comprises single-ended signaling. The method also determines the speed of the electrical signal. Additionally, the method converts the electrical signal of the first protocol into an electrical signal of a second protocol based on the speed of the electrical signal. The second protocol comprises differential signaling. Furthermore, the method sends the electrical signal of the second protocol to a second device. In addition, the method stops the electrical signal of the second protocol to the second device when the electrical signal of the second protocol indicates an end of data flow.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.13/539,377, filed on Jun. 30, 2012, entitled “A Clock-Less Half-DuplexRepeater,” the contents of which are hereby incorporated by referencefor all purposes.

BACKGROUND

Modern computing systems can include a variety of communication devicesthat send and receive data. Examples of communication devices includeparallel interface devices and serial interface devices such as theuniversal serial bus (USB). USB is an industry protocol designed tostandardize the interfaces between computer devices for communicationand supplying electrical power. The USB protocol has enjoyed widespreadadoption in nearly every computing device, and has received tremendoussupport in terms of technology development with well-establishedintellectual property (IP) portfolios and standardized softwareinfrastructure.

The standard USB2 specification uses 3.3 Volt analog signaling forcommunications between the two USB2 ports. The 3.3 Volt signal strengthtends to introduce integration challenges because some advancedsemiconductor processes are moving towards a very low geometry leadingto the gate oxide of a CMOS transistor no longer able to tolerate highervoltages, such as 3.3 Volt. In addition, the standard USB2 specificationresults in relatively high levels of power consumption at both idle andactive states. As a result, USB2 may not be suitable for devices thatplace stringent specifications on I/O power consumption, such as mobileplatforms.

BRIEF DESCRIPTION OF THE DRAWINGS

The following detailed description may be better understood byreferencing the accompanying drawings, which contain specific examplesof numerous objects and features of the disclosed subject matter.

FIG. 1 is an example of a block diagram of an eUSB2 enabled host thatuses an eUSB2 repeater to communicate data with a USB device.

FIG. 2 is a process flow diagram of an example of a method ofcommunicating data between two devices with a eUSB2 repeater.

FIG. 3 is an illustration of an example of a eUSB2 repeaterarchitecture.

FIG. 4 is a timing diagram illustrating a High-Speed embodiment of datacommunication between an eUSB2 interface and a USB device through aeUSB2 repeater.

FIG. 5 is a block diagram of an example of a computing system thatcommunicates data between an eUSB2 interface and a USB device.

FIG. 6 is an example of a dual role eUSB2 repeater that communicatesdata between two devices.

FIG. 7 is an illustration of an example eUSB2 repeater state machine.

DESCRIPTION OF THE EMBODIMENTS

eUSB2 is a newly proposed input/output (IO) solution that aims to reducethe voltage cost and power consumption of USB 2.0 interfaces. eUSB2 uses1.0 Volt (V) digital signaling instead of the 3.3 Volt analog signal inUSB 2.0 Low-Speed (LS) and Full-Speed (FS) operations. Additionally,eUSB2 uses 0.2 V differential signaling instead of the 0.4 Vdifferential signaling for USB 2 High-Speed (HS) interfaces. Due to thedifferences in the signal strength of USB2 and eUSB2, a eUSB2 repeatermay be used as an electrical bridging solution to ensure that these twoIO implementations may communicate with each other.

According to embodiments of the subject matter disclosed in thisapplication, a clock-less half-duplex eUSB2 repeater is used to bridgecommunications between a USB2 interface and a low-voltage signalinginterface such as eUSB2. A clock-less half-duplex eUSB2 repeater, alsoreferred to herein as an eUSB2 repeater, is a device that cancommunicate data between a standard USB2 interface and a low-voltagesignaling interface without a clock source, such as a phase locked loop(PLL), as an input. A clock-less half duplex eUSB2 repeater may notimplement clock data recovery to decode and retime a data packet. Thetraffic flow control in a clock-less half duplex repeater can beimplemented by detecting the raw electrical signaling level. Alow-voltage signaling interface, as referred to herein, includes anydevice that can send or receive data through a universal serial bus at alow-voltage. For example, an eUSB2 interface is a low-voltage signalinginterface that may send and receive data at 0.2 V for high-speed datatransmission, while a standard USB2 interface may send and receive dataat a higher voltage of 0.4 V for high-speed data transmission. A lowvoltage, as referred to herein, includes any voltage used to transmitdata by an eUSB2 protocol. A high voltage, as referred to herein,includes any voltage used to transmit data by a standard USB2 protocol.

Reference in the specification to “one embodiment” or “an embodiment” ofthe disclosed subject matter means that a particular feature, structure,or characteristic described in connection with the embodiment isincluded in at least one embodiment of the disclosed subject matter.Thus, the phrase “in one embodiment” may appear in various placesthroughout the specification, but the phrase may not necessarily referto the same embodiment.

FIG. 1 is an example of a block diagram of an eUSB2 enabled host thatuses an eUSB2 repeater to communicate data with a standard USB2 device.In some embodiments, the eUSB2 enabled host 100 may be a computingsystem that includes an eUSB2 interface 102. The eUSB2 interface 102 cancommunicate data through data wires eD+/eD− 104 at a lower-voltage.

In this example, an eUSB2 repeater 106 allows for the data to becommunicated between an eUSB2 interface 102 and a USB2 device 108. TheeUSB2 host 100 can communicate with USB2 device 108 at low speed, fullspeed or high speed. The USB2 device 108 may be connected to the eUSB2repeater 106 by a pair of USB2 data wires D+/D− 110 and a connector 112.The eUSB2 interface 102 may be connected to the eUSB2 repeater 106 by apair of eUSB2 data wires eD+/eD− 114. The connector 112 allows for theUSB2 device 108 to send and receive data from the eUSB2 repeater 106.The USB2 device 108 can communicate using any universal serial busprotocol. For example, the USB2 device may include functionality tocommunicate with other devices with a USB 1.0 or USB 2.0 protocol.

In some embodiments, the eUSB2 repeater 106 can detect and forward datathat is received from either the USB2 device 108 or eUSB interface 102.For example, the eUSB2 repeater 106 may detect a sequence of electricalsignals that represent data to transmit from the eUSB2 interface 102 tothe USB2 device 108 at a high speed. In other embodiments, the eUSB2repeater 106 can detect and execute commands. For example, the eUSB2repeater may be configured to detect a disconnect command whichinstructs the eUSB2 repeater to stop sending electrical signals to aslave drive. In the example illustrated in FIG. 1, the eUSB2 repeater106 may stop sending electrical signals to the USB2 device 108 after theeUSB2 repeater 106 receives a disconnect command.

FIG. 2 is a process flow diagram of an example of a method ofcommunicating data between a eUSB2 host and a USB2 device through aneUSB2 repeater. In some embodiments, the eUSB2 repeater can beimplemented as a component of a computing system. In these embodiments,the eUSB2 repeater can allow an eUSB2 interface of the computing systemto communicate data with another device, such as a USB2 device, that isconnected to the computing system.

At block 202, a eUSB2 repeater 106 detects an electrical signal from afirst device. The electrical signal can include a sequence of analog ordigital signals that can transmit data or instructions. For example, anelectrical signal can include an instruction to access data that residesin a USB2 device and return the data to a computing system connected tothe USB2 device. The electrical signals can be transmitted by variousprotocols. For example, the electrical signals can be transmitted as asingle-ended signaling protocol or a differential signaling protocol.Single-ended signaling, as referred to herein, includes signals that aretransmitted on one of two data lines. For example, data may betransmitted along eD− while the eD+ data line receives consecutivelogical 0's. The differential signaling protocol, as referred to herein,includes transmitting data with two complementary signals along two datalines. For example, differential signaling may indicate that a sequenceof logical 0's transmitted along a data line D+ may also include asequence of logical 1's transmitted along a data line D−. Single-endedand differential signaling are described further in co-pending patentapplication Ser. No. ______, filed on Jun. 30, 2012, titled “A Low PowerUniversal Serial Bus,” which is incorporated by reference herein in itsentirety for all purposes.

At block 204, a eUSB2 repeater 106 determines the speed of theelectrical signal. In some embodiments, the eUSB2 repeater 106 maydetect electrical signals transmitted at a low speed (LS), a full speed(FS), or a high speed (HS). The LS, FS, and HS signals can have speedsindicated according to the standards for universal serial buses.Electrical signals transmitted at a low speed can take a longer periodof time to transmit data between a computing system and a USB device.Additionally, electrical signals transmitted at a low or full speed cantransmit data at a higher voltage than data transmitted by a high speedtransmission. For example, a USB2 device may transmit a high speedelectrical signal at 0.4 V, while the USB2 device may transmit a low orfull speed electrical signal at up to 3.3 V.

At block 206, an eUSB2 repeater 106 determines the data flow direction.The data flow direction, as referred to herein, can indicate the flow ofdata between an eUSB2 host and a standard USB2 device. For example, thedata flow direction may indicate an upstream direction in which data istransmitted from an eUSB2 host to a standard USB2 device. In otherexamples, the data flow direction may indicate a downstream direction inwhich data is transmitted from a standard USB device to an eUSB2 host.In some embodiments the eUSB2 repeater 106 can include a multiplexer.The eUSB2 repeater 106 can send the low voltage signal to a multiplexerand the multiplexer can select a data flow direction.

At block 208, the eUSB2 repeater 106 converts the electrical signal intoa low voltage signal. As discussed above, the eUSB2 interface maytransmit and receive data at a lower voltage than USB2 devices. Forexample, eUSB2 may use 1.0 Volt (V) digital signaling instead of the 3.3Volt analog signal in USB 2.0 Low-Speed (LS) and Full-Speed (FS)operations. In other examples, eUSB2 may use 0.2 V differentialsignaling instead of the 0.4 V differential signaling for USB2High-Speed (HS) interfaces. In this example, the eUSB2 repeater 106 mayconvert the electrical signal into a low voltage signal based on thespeed of the transmission of data.

At block 210, the eUSB2 repeater 106 sends the low voltage signal to asecond device. In some embodiments, the second device may include aneUSB2 interface. The second device can detect the low voltage signal andretrieve the data from the low voltage signal. In some embodiments, thedata included in the low voltage signal can represent data orinstructions to be executed on the second device.

At block 212, the eUSB2 repeater 106 stops sending the low voltagesignal to the second device. In some embodiments, the eUSB2 repeater 106may detect a sequence of electrical signals transmitted within the lowvoltage signal that indicates the data transmission has completed. Forexample, a sequence of “0110” may indicate to the eUSB2 repeater 106that the data transmission is to be terminated between the first deviceand the second device. In other embodiments, the eUSB2 repeater 106 candetect and execute commands in electrical signals sent from a USB2device or eUSB2 interface. For example, the eUSB2 repeater 106 candetect a SYNC command and detect data followed by the SYNC command tosend to the second device. The process ends at block 214.

The process flow diagram of FIG. 2 is not intended to indicate that thesteps of the method 200 are to be executed in any particular order, orthat all of the steps of the method 200 are to be included in everycase. Further, any number of additional steps may be included within themethod 200, depending on the specific application. For example, in someembodiments the eUSB2 repeater 106 can enter an idle state while waitingfor a subsequent transmission of data between the first device and thesecond device. Additionally, electrical signals can be sent from a USB2device to an eUSB2 interface. For example, a high voltage signal can besent to the eUSB2 repeater 106, which can convert the high voltagesignal into a low voltage signal and send the low voltage signal to theeUSB2 interface. The conversion of a high voltage signal to a lowvoltage signal can include reducing the voltage of a low or full speedtransmission from 3.3 V to 1.0 V or reducing the voltage of a high speedtransmission from 0.4 V to 0.2 V.

FIG. 3 is an illustration of an example of an eUSB2 repeaterarchitecture. The eUSB2 device port 302 can send and receive data in alow-voltage signal such as eD+ and eD− 304. The standard USB2 host port306 can send and receive data in a high voltage signal such as D+ and D−308. The eUSB2 repeater 310 can convert the low-voltage signal 304 intoa high voltage signal 308 and a high voltage signal 308 to a low voltagesignal 304 using a repeater state machine 312 and two voltagelevel-shifting multiplexers 314 and 316. The low voltage signals 304 andhigh voltage signals 308 can provide the eUSB2 repeater 310 with data tosend the eUSB2 device port 302 or the standard USB2 host port 306. Insome embodiments, the low voltage signals 304 and high voltage signals308 can transmit commands for the eUSB2 repeater 310 to execute. Forexample, a command to reset the eUSB2 repeater state machine 312 can beexecuted without sending the command to the standard USB2 host port 306.

The eUSB2 repeater 310 can respond to control or configuration commandsreceived from the low voltage signals 304 or high voltage signals 308 byentering any number of states. For example, an idle state can result ifthe eUSB2 repeater 310 commands the eUSB2 device port 302 to enable thesingle ended receivers, enable the control signal detector, and enablethe squelch detector while disabling the receiver termination if thesignal is high speed. The single ended receivers can receive data on oneof two data lines. For example, data may be transmitted along D− whilethe D+ data line receives a logical 0. The control signal detector canindicate if a command has been received by the eUSB2 repeater 310. Thesquelch detector, also referred to as a squelch circuit, can detect ifan electrical signal received by the eUSB2 repeater 310 is above athreshold, which indicate valid data bit for repeater to act on. In someembodiments, the eUSB2 repeater 310 may request that the standard USB2host port 306 follow standard procedures defined by the USB2 standard.If the eUSB2 repeater 310 exits from an idle state after detecting aSYNC command, the eUSB2 repeater 310 can detect a low voltage signal 304from the eUSB2 device port 302. The eUSB2 repeater 310 may not recoveror decode the SYNC command, but the eUSB2 repeater 310 can detect thesignal amplitude of the SYNC command. In High-speed mode, a squelchcircuit is used to detect the signal amplitude of the SYNC command andto indicate if the SYNC command is valid. In Low-speed and Full-speedmodes, a single-ended receiver is used to detect the signal amplitude ofthe SYNC command and to indicate if the SYNC command is valid. The SYNCcommand indicates the repeater is to forward data in an electricalsignal to a second device. If the eUSB2 repeater 310 exits from an idlestate after receiving a SYNC command, the eUSB2 repeater 310 can receivea converted high voltage signal 306. The eUSB2 repeater 310 can alsoenter a “low speed keep alive” state if a keep alive control signal isreceived and forward the keep alive control signal to the destinationdevice following the defined signaling format. The eUSB2 repeater 310can enter an idle state if a control signal of Suspend is received ateD+/eD− 304. Control message signaling is described further inco-pending patent application Ser. No. ______, filed on Jun. 30, 2012,titled “Explicit Control Message Signaling,” which is incorporated byreference herein in its entirety for all purposes. The eUSB2 repeater310 can enter reset if a reset control signal is received. The eUSB2repeater 310 can enter a connect state if device disconnect is detected.

The eUSB2 310 can also enter a receive state in which USB packets arereceived from D+/D− 308. If the eUSB2 repeater 310 is receiving USB2packets, the eUSB2 repeater 310 can operate at REP mode and the eUSB2repeater 310 can forward the USB2 packets upon detection of anun-squelch condition at D+/D− 308. REP mode and NREP mode are discussedin greater detail below in relation to FIG. 7.

In some embodiments, the eUSB2 repeater 310 can enter an idle state upondetection of squelch condition at D+/D− 308. A squelch condition mayoccur when a squelch circuit included in the repeater state machine 312indicates an absence of electrical signal has been detected. The squelchcondition may include a threshold value. If an electrical signal isdetected above the threshold value, the squelch circuit can indicate anelectrical signal has been detected. If an electrical signal is detectedbelow the threshold value, the squelch circuit can indicate theelectrical signal is an erroneous signal. For example, the squelchcircuit may detect a faint electrical signal below a threshold that is aresult of the physical operating environment such as static electricity.

In some embodiments, if the eUSB2 repeater 310 detects a USB2 packet,the eUSB2 repeater 310 forwards the USB2 packet to D+/D− 308. The eUSB2repeater 310 can forward the USB packet in REP mode. While forwardingdata to D+/D− 308, the eUSB2 repeater 310 can maintain a device pingcounter to track the transmission of a device ping. A device ping, asreferred to herein, includes a logical 1 signal from eD− in a Full speedor Low speed transmission or 8 unit intervals (UI) of static bit inHigh-speed transmission. The repeater eUSB2 port, upon device pingcounter timeout, can periodically send a device a ping signal toindicate the presence of a device. In some embodiments, when the eUSB2repeater 310 stops receiving low voltage signals 304 from the eUSB2 port302, the eUSB2 repeater 310 can enter the idle state. For example, theeUSB2 repeater 310 can enter the idle state if the eUSB2 repeater 310has completed the transmission of USB packet at D+/D− 308.

FIG. 4 is a timing diagram illustrating a High-Speed embodiment of datacommunication between an eUSB2 interface 400 and a USB2 device 402through an eUSB2 repeater 404. As discussed above in regard to FIG. 1,the eUSB2 repeater 404 can send and receive data on data lines such aseD+, eD−, D+, and D−. In some embodiments, the data lines eD+ and eD−406 transmit data at a lower voltage, while data lines D+ and D− 408 cantransmit data at a higher voltage. The data lines 406 and 408 can alsotransmit commands between the eUSB2 interface 400 and the USB2 device402. In some embodiments, the commands are represented by a series oflogical 1's and logical 0's. A logical ‘1’ can describe a state of adata line in which a voltage at the data line is above a threshold. Forexample, a threshold may indicate any voltages above a certain value areto be considered a logical ‘1.’ A logical ‘0’ can describe a state of adata line in which a voltage at the data line is below a threshold.Block J refers to a differential-1 data state, where eD+ is a logical‘1’ and eD− is a logical ‘0’. Block K refers to a differential-0 datastate, where eD+ is a logic ‘0’ and eD− is a logical ‘1’.

The example of a communication between the eUSB2 interface 400 and theUSB2 device 402 illustrated in FIG. 4 includes the eUSB2 interface 400sending (as indicated by the circled 1) an electrical signal to the USB2device 402 along the data lines eD+ and eD− 406. The eUSB2 data 410represents the data transmitted by the data lines 406. As data istransmitted to the eUSB2 repeater 404 from the eUSB2 interface 400, theeUSB2 data indicates a block K followed by a block J. The eUSB2 data 410also includes a repeat of the block K followed by the block J. Thesecond repetition of the blocks K and J in eUSB2 data 410 indicates tothe eUSB2 repeater 404 that the eUSB2 interface 400 is transmitting datato the USB2 device 402. The eUSB2 repeater 404 may select a downstreamdata direction with a multiplexer to allow the data to be transmittedfrom the eUSB2 interface 400 to the USB2 device 402. In someembodiments, the multiplexer may wait a predetermined period of timebefore selecting the data direction. For example, the multiplexer maywait to receive two logical data signals before selecting the datadirection. The eUSB2 repeater 404 can convert the eUSB2 data 410 to USB2data 414 by amplifying the voltage of the eUSB2 data 410 to form USB2data 414. For example, the eUSB2 data 410 may be amplified from 0.2 V to0.4 V for a high speed transmission of data. The USB2 device 402 canretrieve the USB2 data at 414.

In some embodiments, the USB2 device 402 and the eUSB2 interface 400 cantransmit data when the USB2 device sends (as indicated by the circled 2)an electrical signal to the eUSB2 device 400 through the data lines D+and D− 408. The USB2 data at 414 represents the data transmitted throughthe data lines D+ and D− 408. As data is transmitted to the eUSB2repeater 404 from the USB2 device 402, the USB2 data 414 indicates ablock K followed by a block J. The USB2 data 414 can also include arepeat of the block K followed by the block J. The second repetition ofblocks K and J in the USB2 data 414 indicates to the eUSB2 repeater 404that the USB2 device 402 is transmitting data to the eUSB2 interface400. The eUSB2 repeater 404 may select an upstream data direction with amultiplexer at 416 (also illustrated in FIG. 3 at blocks 314 and 316) toallow the data to be transmitted from the USB2 device 402 to the eUSB2interface 400. A single-ended receiver is used to generate the signalfor the multiplexer when the speed of the data transmission is low speedor full speed. A squelch circuit is used to generate the signal for themultiplexer when the speed of the data transmission is high speed. TheeUSB2 repeater 404 can convert the USB2 data 414 to eUSB2 data 410 byreducing the voltage of the USB2 data 414 to form eUSB2 data 410. Forexample, the USB2 data 414 may be reduced from 0.4 V to 0.2 V for a highspeed transmission of data. The eUSB2 interface 400 can then retrievethe eUSB2 data 410.

It is to be understood that FIG. 4 is included for illustrative purposesand additional devices may be used to communicate data between the eUSB2interface 400 and the USB2 device 402. For example, a connector mayforward the data between the eUSB2 repeater 404 and the USB2 device 402.Furthermore, the eUSB2 repeater architecture can be used to communicatedata between two devices that do not include an eUSB2 interface. In someembodiments, the eUSB2 repeater architecture may communicate databetween any two devices that support a parallel or serial interface. Forexample, the eUSB2 half-duplex repeater architecture may be used tocommunicate data between a USB 1.0 device and a USB 2.0 device.

FIG. 5 is a block diagram of an example of a computing system thatcommunicates data between an eUSB2 interface and a USB2 device. Thecomputing system 500 may be, for example, a mobile phone, laptopcomputer, desktop computer, or tablet computer, among others. Thecomputing system 500 may include a processor 502 that is adapted toexecute stored instructions, as well as a memory device 504 that storesinstructions that are executable by the processor 502. The processor 502can be a single core processor, a multi-core processor, a computingcluster, or any number of other configurations. The memory device 504can include random access memory (e.g., SRAM, DRAM, zero capacitor RAM,SONOS, eDRAM, EDO RAM, DDR RAM, RRAM, PRAM, etc.), read only memory(e.g., Mask ROM, PROM, EPROM, EEPROM, etc.), flash memory, or any othersuitable memory systems.

The processor 502 may be connected through a system bus 506 (e.g., PCI,ISA, PCI-Express, HyperTransport®, NuBus, etc.) to an input/output (I/O)device interface 508 adapted to connect the computing system 500 to oneor more I/O devices 510. The I/O devices 510 may include, for example, akeyboard and a pointing device, wherein the pointing device may includea touchpad or a touchscreen, among others. The I/O devices 510 may bebuilt-in components of the computing system 500, or may be devices thatare externally connected to the computing system 500.

The processor 502 may also be linked through the system bus 506 to adisplay interface 512 adapted to connect the computing system 500 to adisplay device 514. The display device 514 may include a display screenthat is a built-in component of the computing system 500. The displaydevice 514 may also include a computer monitor, television, orprojector, among others, that is externally connected to the computingsystem 500.

A network interface card (NIC) 516 may be adapted to connect thecomputing system 500 through the system bus 506 to a network (notdepicted). The network (not depicted) may be a wide area network (WAN),local area network (LAN), or the Internet, among others.

An eUSB2 interface 518 may be adapted to connect to the computing system500 through the system bus 506. The eUSB2 interface 518 may transmit andreceive data from USB devices 520 through a eUSB2 repeater 522. TheeUSB2 repeater 522 can convert high voltage signals into low voltagesignals.

It is to be understood that the block diagram of FIG. 5 is not intendedto indicate that the computing system 500 is to include all of thecomponents shown in FIG. 5. Rather, the computing system 500 can includefewer or additional components not illustrated in FIG. 5 (e.g.,additional USB ports, additional eUSB2 interfaces, additional networkinterfaces, etc.). Furthermore, any of the functionalities of the eUSB2repeater 522 may be partially, or entirely, implemented in hardwareand/or in the processor 502. For example, the functionality may beimplemented with an application specific integrated circuit or in logicimplemented in the processor 502, among others.

FIG. 6 is an example of a dual role eUSB2 repeater that communicatesdata between a host and a device. In some embodiments, the two devicesinclude an eUSB2 host 602 and a standard USB2 device 604. The dual roleallows each device to function as a device and a host. For example, if astandard USB2 device is connected to a computing system with an eUSB2interface, the standard USB2 device may be able to transmit data to thecomputing system as a host or a device.

In some embodiments, the eUSB2 repeater 606 supports a static Dual RoleFunction, which is an extension of host mode eUSB2 repeater 606. TheStatic Dual Role Function is a commonly used On-the-Go (also referred toherein as OTG) mode. AN On-the-Go mode, as referred to herein, is aprotocol that allows a standard USB device or eUSB2 device to act asboth a host and a device. For example, a digital audio player connectedto a computing system can host the computing system by controlling theflow of data.

In some embodiments, the eUSB2 repeater 606 can transmit data from aneUSB2 host 602 to a USB2 device 604. The eUSB2 host 602 may schedule andconfigure data transfers over the data wires 608. The USB2 device 604 isa device, which may not be able to initiate data transfers. As a device,the USB2 device 604 may respond to requests for data sent by the eUSB2host 602.

In some embodiments, the eUSB2 repeater 606 can transmit data from aUSB2 host 610 to an eUSB2 device 612 through data lines 614. The USBhost 610 may schedule and configure data transfers over the data wires614. The eUSB2 device 612 is a device in this example, so the eUSB2device 612 may not be able to initiate data transfers. As a device, theeUSB2 device 612 may respond to requests for data sent by the USB2 host610.

In some embodiments, an eUSB2 repeater 606 can determine the role of anOTG capable port by the polarity of the ID pin. For example, the eUSB2repeater 606 can determine the polarity of the ID pin when an OTGcapable port is connected to a non-OTG capable host or device. In someexamples, an OTG capable device has a micro-AB receptor. When a micro-Aplug is inserted, the OTG device can present itself as a hostenumerating the device. If a micro-B plug is inserted, the OTG devicecan function as a pre-defined device function, such as a mass storage.

FIG. 7 is an illustration of an example eUSB2 repeater state machine.The power-up block 702 indicates the eUSB2 repeater is connected to apower source. In some embodiments, upon power up by the system, theeUSB2 repeater may enter non-repeater mode (NREP) 704 where it mayinitialize itself for standard USB2 device connect detection andsubsequent operations relating to device initialization such as resetbased on control message and speed negotiation. Once the deviceinitialization is complete, the eUSB2 repeater may enter a repeater(REP) mode 706 ready for USB2 data packet forwarding between a eUSB2enabled host and a standard USB2 device.

Although some embodiments have been described in reference to particularimplementations, other implementations are possible according to someembodiments. Additionally, the arrangement or order of circuit elementsor other features illustrated in the drawings or described herein neednot be arranged in the particular way illustrated and described. Manyother arrangements are possible according to some embodiments.

In each system shown in a figure, the elements in some cases may eachhave a same reference number or a different reference number to suggestthat the elements represented could be different or similar. However, anelement may be flexible enough to have different implementations andwork with some or all of the systems shown or described herein. Thevarious elements shown in the figures may be the same or different.Which one is referred to as a first element and which is called a secondelement is arbitrary.

In the description and claims, the terms “coupled” and “connected,”along with their derivatives, may be used. It should be understood thatthese terms are not intended as synonyms for each other. Rather, inparticular embodiments, “connected” may be used to indicate that two ormore elements are in direct physical or electrical contact with eachother. “Coupled” may mean that two or more elements are in directphysical or electrical contact. However, “coupled” may also mean thattwo or more elements are not in direct contact with each other, but yetstill co-operate or interact with each other.

An embodiment is an implementation or example of the inventions.Reference in the specification to “an embodiment,” “one embodiment,”“some embodiments,” or “other embodiments” means that a particularfeature, structure, or characteristic described in connection with theembodiments is included in at least some embodiments, but notnecessarily all embodiments, of the inventions. The various appearances“an embodiment,” “one embodiment,” or “some embodiments” are notnecessarily all referring to the same embodiments.

Not all components, features, structures, characteristics, etc.described and illustrated herein need be included in a particularembodiment or embodiments. If the specification states a component,feature, structure, or characteristic “may”, “might”, “can” or “could”be included, for example, that particular component, feature, structure,or characteristic is not required to be included. If the specificationor claim refers to “a” or “an” element, that does not mean there is onlyone of the element. If the specification or claims refer to “anadditional” element, that does not preclude there being more than one ofthe additional element.

Although flow diagrams and state diagrams may have been used herein todescribe embodiments, the inventions are not limited to those diagramsor to corresponding descriptions herein. For example, flow need not movethrough each illustrated box or state or in exactly the same order asillustrated and described herein.

The inventions are not restricted to the particular details listedherein. Indeed, those skilled in the art having the benefit of thisdisclosure will appreciate that many other variations from the foregoingdescription and drawings may be made within the scope of the presentinventions. Accordingly, it is the following claims including anyamendments thereto that define the scope of the inventions.

1-20. (canceled)
 21. A universal serial bus repeater, comprising: afirst universal serial bus port to be coupled to a first low voltagesignal line and to a second low voltage signal line; a second universalserial port to be coupled to a first high voltage signal line and to asecond high voltage signal line; and a controller to control a directionof data flow of the first universal serial bus port and the seconduniversal serial bus port.
 22. The universal serial bus repeater ofclaim 21, wherein the first low voltage signal line and the second lowvoltage signal line use 1 volt digital signaling.
 23. The universalserial bus repeater of claim 21, wherein the first high voltage signalline and the second high voltage signal line use 3.3 volt analogsignaling.
 24. The universal serial bus repeater of claim 21, whereinthe first low voltage signal line and the second low voltage signal lineuse 1 volt digital signaling and wherein the first high voltage signalline and the second high voltage signal line use 3.3 volt analogsignaling.
 25. The universal serial bus repeater of claim 21, whereinthe first low voltage signal line and the second low voltage signal lineuse 0.2 volt differential signaling.
 23. The universal serial busrepeater of claim 21, wherein the first high voltage signal line and thesecond high voltage signal line use 0.4 volt differential signaling. 24.The universal serial bus repeater of claim 21, wherein the first lowvoltage signal line and the second low voltage signal line use 0.2 voltdifferential signaling and wherein the first high voltage signal lineand the second high voltage signal line use 0.4 volt differentialsignaling.
 25. The universal serial bus repeater of claim 21, whereinthe first universal serial bus port is an eUSB2 port.
 26. The universalserial bus repeater of claim 21, wherein the second universal serial busport is a USB2 port.
 27. The universal serial bus repeater of claim 21,wherein the first universal serial bus port is an eUSB2 port and thesecond universal serial bus port is a USB2 port.
 28. The universalserial bus repeater of claim 21, wherein the repeater is a half-duplexanalog repeater.
 29. The universal serial bus repeater of claim 21,wherein the controller comprises a repeater state machine.
 29. Theuniversal serial bus repeater of claim 21, wherein the controllercomprises a repeater state machine and one or more multiplexers.
 30. Theuniversal serial bus repeater of claim 21, wherein the first port is toreceive data from and is to transfer data to the first and second lowvoltage signal lines.
 31. The universal serial bus repeater of claim 21,wherein the second port is to receive data from and is to transfer datato the first and second high voltage signal lines.
 32. The universalserial bus repeater of claim 21, wherein the first port is to receivedata from and is to transfer data to the first and second low voltagesignal lines, and wherein the second port is to receive data from and isto transfer data to the first and second high voltage signal lines. 33.The universal serial bus repeater of claim 21, wherein the controller isto detect an electrical signal of a first protocol from the first portor the second port, to determine a data flow direction, to convert theelectrical signal to a second protocol, and to send the electricalsignal of the second protocol to the other of the first port or thesecond port.
 34. The universal serial bus repeater of claim 33, whereinthe first protocol comprises single-ended signaling and the secondprotocol comprises differential signaling.
 35. The universal serial busrepeater of claim 33, wherein the electrical signal of the firstprotocol comprises a command to be executed by the repeater.
 36. Theuniversal serial bus repeater of claim 35, wherein the command to beexecuted by the repeater comprises a disconnect command that stops therepeater from forwarding the electrical signal.
 37. The universal serialbus repeater of claim 35, wherein the command to be executed by therepeater comprises a SYNC command that indicates the repeater is toforward data in the electrical signal to the second device.
 38. Theuniversal serial bus repeater of claim 35, wherein the controller is todetect and send data that follows the command to be executed by therepeater and is to be transmitted from the repeater.
 39. The universalserial bus repeater of claim 33, wherein the electrical signal of thesecond protocol indicates the end of data flow with a sequence ofelectrical signals.
 40. The universal serial bus repeater of claim 35,wherein the speed of the electrical signal of the first protocolcomprises a low speed, a full speed, or a high speed.
 41. The universalserial bus repeater of claim 33, the controller to stop the electricalsignal of the second protocol when the electrical signal of the secondprotocol indicates an end of data flow.
 42. The universal serial busrepeater of claim 21, wherein the controller is to multiplex data flowbetween the first port and second port.
 43. The universal serial busrepeater of claim 21, wherein the controller is to multiplex data flowbetween the first port and second port based on input from asingle-ended receiver or a squelch circuit.
 44. The universal serial busrepeater of claim 21, wherein the direction of data flow comprises anupstream data flow indication or a downstream data flow indication. 45.The universal serial bus repeater of claim 21, wherein the controller isto wait a predetermined period of time before selecting the direction ofdata flow.
 46. The universal serial bus repeater of claim 21, whereinthe controller is to detect a command for the repeater in an electricalsignal received at the first and/or second low voltage signal lines orat the first and/or second high voltage signal lines.